[12.x] cast Batch::progress() return value to int

[zjbarg]

The documented return type for the Batch::progress() method is integer but the round function returns float even though it doesn't contain any decimals.

This will cause a TypeError when the value is float and is consumed by a function expecting an integer in strict mode declare(strict_type=1);

To resolve this issue, the rounded value should be cast to an integer.

Edit:

• return value update to int<0, 100> - suggested by @shaedrich